1. Field of the Invention
The present invention relates generally to apparatus and methods for winding and forming motors, and, more particularly, to apparatus and methods for winding and forming linear motors to increase the parallel arrangement between windings and to produce higher accuracies between phases of the motor. Particular utility for the present invention is in winding one or more phases of a linear motor, although the present invention can also be used for winding rotary motor coils, and for ironless, toothless linear motors and iron core, toothless linear motors.
2. Background Discussion
The current practice in linear and often rotary motor manufacturing is to wind each coil (phase) separately and to then form each single wound coil independently, such that each coil phase will occupy a space proportionate to a single pole in a multi-pole motor assembly. This is illustrated in FIG. 1 of U.S. Pat. No. 4,839,543. This figure depicts nine individually formed coils that make up the poles of a three-phase motor. The coils are wound by hand or on a xe2x80x9cbobbin winderxe2x80x9d and are then assembled by interleaving into finished form.
The forming process is generally associated with each single wound coil phase, and is typically done in a flat fixture. The winding must be confined in all directions to result in final, finished dimensions. The coils are toleranced to minimize the impact on the final assembly, however, some sub-optimal result is anticipated due to needed clearance gaps between the coils caused by erratic tolerance accumulations between the coils and in the finished assembly. This process results in a coil assembly with low conductor density and high phase position error as compared to the present invention.
If each single wound coil phase is not formed separately but as an entire assembly, the unconstrained conductors of each coil intermingle and can thereby be offset from their proper phase position. This reduces the motor performance, since conductors in a given coil not constrained to the given design space work against the forces generated by the properly positioned conductors. The cost and time associated with assembling and handling the multiple individual coils throughout the manufacturing process is also a disadvantage.
Accordingly, the present invention provides apparatus and methods of winding and forming a linear motor where multi-phase coils are wound and formed as single assembly. In the preferred embodiment, winding is achieved on a winding machine. This machine is essentially a multi-axis robot providing movement of a needle relative to a winding fixture. The winding machine for the linear motor provides a mechanical base for a plurality of winding configurations. This winding machine provides several axis of motion, safety monitors, quality assurance devices and programmable winding features for linear and rotary motor coils. The winding machine feeds and manipulates the magnet wire through a small diameter wire guide (needle) made of steel, ceramic or equivalent material. Accurate tensioners are provided to ensure proper wire tension during the winding process. The wire is laid over pins such that the coil forms a shape similar to the final motor configuration. This needle is attached to the central xe2x80x9cXxe2x80x9d and xe2x80x9cYxe2x80x9d axis to provide motion across and above the winding fixture. The winding fixture is attached to a rotational axis providing rotary capability to the winding process. Minimal component specific tooling is required to complete the mechanical changeover between rotary and linear designs, or multiple configurations of the same design.
The linear motor coil is wound with a xe2x80x98bondablexe2x80x99 magnet wire. This wire has a special bonding material applied over the insulation coating that acts as an impregnant, partially surrounding each individual conductor when heated to the proper temperature. The bonding agent is a thermosetting epoxy that results in a structure that will not melt or sag when subjected to heat from subsequent operations or from a finished coil assembly under load.
Winding multiple phases on precisely placed pins provides the relative positioning of the coils by laying each group of copper conductors in precise position relative to one another. Additionally, assembly time is thereby reduced.
In one embodiment, the present invention provides a coil winding fixture, comprising: a first interchangeable winding arm having a first set of a plurality pins extending therefrom, said first plurality pins defining a first plurality of slots between two adjacent pins; a second interchangeable winding arm having a second set of a plurality pins extending therefrom, said second plurality pins defining a second plurality of slots between two adjacent pins; said first and second winding arms held in fixed relationship to one another so that said first and second plurality of pins are held at angles to one another, and so that said first plurality of slots and said second plurality of slots are held in parallel with respect to adjacent slots, so that magnetic wire can be wound around said pins and placed in the first and second plurality of slots.
In a system level embodiment, a coil winding system is provided that comprises: a winding machine for controlling a winding fixture in a rotational axis and a winding needle in a linear axis; said winding fixture comprising a first interchangeable winding arm having a first plurality of in-line pins extending therefrom, said first plurality pins defining a first plurality of slots between two adjacent pins; a second interchangeable winding arm having a second plurality of in-line pins extending therefrom, said second plurality pins defining a second plurality of slots between two adjacent pins; said first and second winding arms held in fixed relationship to form a winding fixture; said winding needle mounted on a needle arm, said needle arm mounted in a predetermined location with respect to said first and second in-line pins; said winding machine controlling the linear motion of said needle arm and said winding needle along said linear axis and the rotational motion of said winding fixture in said rotational axis to cause said winding needle to place magnet wire in a selected one of said slots.
A coil forming fixture is also provided that comprises: a bottom forming block having a slot dimensioned to receive a coil winding structure and a removable saddle placed in said slot for holding the coil winding structure on the face of the saddle; a top forming block placed over said coil winding structure, said-saddle and said bottom forming block; and a press placed over said top forming block and removably attached to said bottom forming block.
In method form, the present invention provides a process for coil winding that comprises the steps of: positioning magnetic coil wire adjacent to a first predetermined slot in a winding fixture; rotating said coil winding fixture to place said wire into said predetermined slot; positioning said wire adjacent to a predetermined second slot in said winding fixture, said second slot being a predetermined distance from said first slot; and rotating said coil winding fixture to place said wire into said predetermined other slot.
This winding techniques and apparatus provided by the present invention can be applied in both ironless, toothless linear motors and iron core, toothless linear motors where multiple phases are wound and phase position significantly impacts motor performance. The winding strategy provided herein to wind all phases together whenever possible eliminates handling, and provides an accurate method for wire placement and reduction of end turns, all of which directly impact motor efficiency. Particularly in ironless winding configurations (ironless motor designs), the form shape and size of the winding is paramount to the performance of the wound assembly.
It will be appreciated by those skilled in the art that although the following Detailed Description will proceed with reference being made to preferred embodiments, the present invention is not intended to be limited to these preferred embodiments. Other features and advantages of the present invention will become apparent as the following Detailed Description proceeds, and upon reference to the Drawings, wherein like numerals depict like parts, and wherein: